r - tidyverse 按列连接两个具有动态列名的数据集

Question

我想加入两个数据框，我需要将“by”列作为动态列传递。我试图在此处遵循此解决方案 ( How to pass column names for inner join by 2 column sets as variables with dplyr )，但仍然出现错误。

library(tidyverse)
x <- data.frame(a1 = c(1, 2, 3))
y <- data.frame(a2 = c(1, 2, 4),
                new = c("a", "b", "c"))

x_name <- "a1"
y_name <- "a2"

x %>%
  left_join(., y, by = setNames(c('x', 'y'), c(x_name, y_name)))

但我会得到以下错误:

Error: Join columns must be present in data.x Problem with a2.

期望的结果:

a1    new
 1      a
 2      b
 3     NA

有什么想法吗？我尝试了多种使用 as.names、!!as.names、paste0...动态传递名称的方法

Answer 1

left_join(x, y, by = setNames(y_name, x_name))
#   a1  new
# 1  1    a
# 2  2    b
# 3  3 <NA>

你的 by= 向量在做什么

setNames(c('x', 'y'), c(x_name, y_name))
#  a1  a2 
# "x" "y" 

而你需要

c(a1 = "a2")
#   a1 
# "a2" 
setNames(y_name, x_name)
#   a1 
# "a2"